Tamper evident labels are used to indicate when a label or a package containing the label has been altered. A problem for retailers and consumers is tampering with packaging of an article. Often the packaged materials are altered and repackaged. This is especially a problem in the area of packaging consumer products, such as compact disks and computer software, and pharmaceuticals. It is desirable to have a label which would show that the product within the packaging had not been opened and altered.
U.S. Pat. No. 4,721,638, issued to Matsuguchi et al, relates to materials that prevent resticking. The materials have an adhesive layer, a second layer, a peeling agent layer laminated on the second layer and a first layer laminated on the peeling agent layer. The second and first layers are adhered via the peeling agent layer. Once the first layer and the second layer are separated they cannot be restuck together. These materials have uses as labels, such as price tags.
U.S. Pat. No. 4,746,556, issued to Matsuguchi et al, relates to easily breakable sticking material. The material has a surface layer, an easily breakable layer laminated to the surface layer, a first peel-off layer formed on the surface of the easily breakable layer, a second peel-off layer formed on a part of the main surface of the easily breakable layer, a covering layer and an adhesive layer. The surface layer is peeled off of the easily breakable layer and cannot be re-adhered again. These materials have use in labels, such as price tags.
U.S. Pat. No. 5,042,842, issued to Green et al, relates to labels, such as those used for preventing or detecting tampering and counterfeiting. The label is a multilayer security label which has a base layer with a permanent adhesive coated on a lower surface. Indicia or markings are applied to the bottom surface of the top layer and the top layer is laminated to the upper surface of the base layer. The top layer is laminated to the upper surface of the base layer by permanent patterned adhesive. A portion of each of the upper surface of the base layer and the bottom surface of the top layer are free of adhesive.